Expanding mandrel

ABSTRACT

An expanding mandrel is useable for rotatably mounting a strip of material that is wound around a sleeve or core. The expanding mandrel includes an ejecting device that is useable to strip the sleeve or core from the mandrel. The ejecting device includes at least a first part, which is rotatable about an axis together with the sleeve or core, and a non-rotatably mounted second part. The first part can strip the sleeve or core from the mandrel by actuation of the second part. That second part is a piston which can be driven by a fluid under pressure.

[0001] The invention relates to a clamping mandrel in accordance with the preamble of claim 1 or 2.

[0002] Clamping mandrels for the rotatable seating of paper rolls, such as are used in connection with web-fed rotary printing presses, are known from U.S. Pat. No. 4,149,682, U.S. Pat. No. 4,951,894 and U.S. Pat. No. 4,715,553. Ejecting devices are provided there on the clamping mandrels, by means of which the tube on which the paper web is wound can be stripped off the clamping mandrels. Spring elements provided on the ejecting device are elastically prestressed in the course of inserting the clamping mandrel into the tube. When the clamping mandrel is pulled back out of the tube for changing the paper web, the prestress of the spring elements assures that the tube is stripped off the two oppositely located clamping mandrels.

[0003] The disadvantage of this type of design of the ejecting device lies in that the force, by means of which the tube can be stripped off the clamping mandrel, is limited by the type of construction of the spring elements. It is moreover necessary to overcome the prestress of the spring elements in the course of inserting the clamping mandrels into the tube.

[0004] A clamping mandrel is known from DE 28 14 338 A1, wherein a displaceable ring, which can rotate together with the mandrel, is arranged between the detent flange of the mandrel and the tube. An actuating device, which is fixed in place on a frame, is provided for ejecting the tube. Claws are provided on the actuating device, wherein the ring can freely rotate in one position of the claws, namely the position of rest, and is not in engagement with the claws. In the course of operating the actuating device the claws are pressed against the ring, so that the tube can be stripped off the clamping mandrel.

[0005] It is disadvantageous in connection with the actuating device known from DE 28 14 338 A1 that, because of its mechanical drive mechanism, the ejecting device requires a large structural volume.

[0006] DE 35 36 1777 Cl, DE 29 48 753 A1, U.S. Pat. No. 2,826,376 and JP 53051 371 A described devices for receiving a wound roll.

[0007] It is the object of the invention to create a clamping mandrel.

[0008] In accordance with the invention, the object is attained by means of the characteristics of claim 1 or 2.

[0009] The advantages which can be achieved by means of the invention lie in particular in that a pressure-charged piston is employed for driving the ejecting arrangement. Since the pressure-containing fluid, for example compressed air or hydraulic fluid, can be conducted to the piston head above the piston through conduits, whose geometry per se can be arbitrarily designed, clamping mandrels of very compact design are possible. It is furthermore possible to generate very high stripping forces by means of selecting a correspondingly high working pressure.

[0010] For reducing the technical outlay in the course of constructing the clamping mandrel it is advantageous if the piston for stripping off the tube is driven by means of the fluid. Elastic spring elements, for example helical springs, can be used for restoring the piston into the initial position.

[0011] Since the ejecting arrangement has an element which can be rotated along with the clamping mandrel and a fixed element, which must be brought into engagement with each other, there is the danger that increased wear occurs in the area of contact between the rotatably seated and stationary elements of the ejecting arrangement. Therefore the embodiment of the ejecting arrangement should be selected to be such, that the second element can be switched between a position of rest and at least one working position. In the position of rest, the first element is completely separated from the second element by a gap, while in the working position it comes to rest against the second element, so that forces for actuating the second element can be transmitted.

[0012] Magnetic elements can be employed particularly advantageously for restoring the second element out of at least one working position. The attractive forces emanating from a magnetic element act in a contactless manner over an air gap, and in this way they can automatically retract the stationary second element, for example an actuating piston, in a particularly simple manner.

[0013] In general it is advantageous in connection with arrangements which have a rotatably seated and axially actuable adjusting element, which can be displaced by means of an axially displaceable, fluid-driven piston between a position of rest and at least one working position, if the piston can be returned from the working position into the position of rest by means of at least one magnetic element. It is possible in this way to prevent wear in the contact zone between the fixed piston and the rotatably seated adjusting element in a simple way, since as long as it is not needed, the piston is automatically retracted in a simple manner by the magnetic element and is dependably maintained there.

[0014] An exemplary embodiment of the invention is represented in the drawings and will be described in greater detail in what follows.

[0015] Shown are in:

[0016]FIG. 1, a clamping mandrel in lateral cross section,

[0017]FIG. 2, the detail X in FIG. 1 in a first operating state,

[0018]FIG. 3, the detail X in FIG. 1 in a second operating state.

[0019] A clamping mandrel 01 is represented in FIG. 1, which is fastened in a frame 02, shown in a broken-off manner, of a roll changer, not further represented. A multi-part shaft 07 is rotatably seated on rolling bearings 04, 06 in the housing 03 of the clamping mandrel 01, which is fixedly connected with the frame 02.

[0020] On the left side of the housing 03, the multi-part shaft 07 extends to the outside of the housing 03 and constitutes a clamping cylinder 08, on which a schematically represented tube 09 can be fixed in place. To fix the tube 09 in place on the clamping mandrel 01, the toggle levers at the provided clamping cheeks 11 are pushed radially outward by means of plate springs and compression springs. An adjusting element 12, for example an actuating shaft 12, can be radially displaced in a hollow shaft 13 for actuating the clamping cheeks 11, so that the clamping cheeks 11 are pushed outward by positive engagement of the spreading elements 14.

[0021] The tube 09 supports a rolled-up web, for example a paper web.

[0022] For stripping the used-up tube 09 off the stripping ring 10, an ejecting arrangement with several actuating elements 16, for example rotatable elements 16, for example ejecting bolts 16, is provided. In this case the ejecting bolts 16 are arranged in such a way on the hollow shaft 13, that the one end of the stripping ring 10 can come to rest against the front face of the tube 09. For the removal of the tube 09, the ejecting bolts 16 are synchronously moved out with the stripping ring 10, and in the course of this they push the tube 09 aside in relation to the clamping cylinder 08. Care should be taken that the ejecting bolts 16 and the stripping ring 10 are seated axially displaceable on the hollow shaft 13 and, together with the hollow shaft 13, rotate in the housing 03 around the center axis 17.

[0023] A non-rotatable element, for example a circle-shaped piston 18, which can be charged with a pressure medium via a pressure line 19, is used for actuating the ejecting bolts 16. The functioning of the actuation of the ejecting bolts 16 by means of the piston 18 is explained by means of drawing FIGS. 2 and 3, which represent the detail X in FIG. 1 in an enlarged manner.

[0024] The piston 18 and the right end of the ejecting bolt 16 can be seen in cross section in FIG. 2. In connection with the operation of the ejecting bolt 16, notice should be taken that the piston 18, together with the housing 03, an intermediate element 21 and the outer ring of the rolling bearing 06, are fixed in place in relation to the frame 02, while the ejecting bolt 16, together with the hollow shaft 13, can rotate around the center axis 17 of the clamping mandrel 01. By means of this it is assured that the piston 18 can be sealed by simple means, which are designed in the manner of piston rings.

[0025] The piston 18 is shown in its position of rest in FIG. 2, in which the ejecting bolt 16 and the piston 18 are separated by a gap 22. In the position of rest of the piston 18, the ejecting bolts 16 can rotate free of wear and resistance around the center axis 17. Magnetic elements 23, for example permanent magnets 23, are fastened to the front face of the piston 18 facing away from the ejecting bolts 16, which pull the piston 18 against the metallic intermediate element 21 and in this way assure that the piston 18 is dependably maintained in the position of rest. The piston 18 is sealed against the housing 03, or the intermediate element 21, by means of seal rings 24, 26, so that it is possible to exert a force directed in the direction of the ejecting bolt 16 by charging the pressure line 19 with a pressure medium.

[0026] In FIG. 3 the piston 18 is represented in its working position. By supplying pressure medium through the pressure line 19, the piston 18 is pushed against the ejecting bolt 16, so that the latter in turn can strip the tube 09 off the clamping cylinder 08. As soon as the tube 09 has been stripped off, the pressure medium is drained from the pressure line 19, so that no pressure forces act on the piston 18 anymore.

[0027] Springs 27, for example helical springs 27, are provided on each of the ejecting bolts 16, which prestress the ejecting bolts 16 against the hollow shaft 13, A restoring force which, following the draining of the pressure medium, assures that the ejecting bolts 16 are again automatically retracted, acts on the ejecting bolts 16 because of the prestress by the helical springs 27. The piston 18 is also pushed back together with the ejecting bolts 16 until the ejecting bolts 16 come into contact with the appropriately provided end stops 28. In this rearmost working position, in which the piston 18 still rests against the ejecting bolt 16, a gap 29 exists between the piston 18 and the intermediate element 21, which must be bridged for returning the piston 18 out of the rearmost working position into the position of rest. By means of the permanent magnets 23 provided on the piston 18, a magnetic force directed toward the right acts on the piston 18, which causes the return of the piston 18 over the gap 29. At the termination of the actuation of the ejecting bolts 16, the piston 18 again takes up its position of rest as represented in FIG. 2, and is separated from the ejecting bolts 16 by the gap 22.

[0028] Since for actuating the rotatably seated ejecting bolts 16 it is merely required to employ the displaceably seated piston 18, the sealing of the work chamber above the piston 18 is greatly simplified. The walls of the piston 18 constituting the sealing gap, on the one hand, and of the housing 03, or of the intermediate elements 21, on the other hand, do not perform any rotationally directed relative movement.

[0029] The end positions of the piston 18 are interrogated by initiators.

[0030] The employment of magnetic elements for uncoupling of a merely can be actuated is conceivable, for example, also in the design actuating device of the clamping cheeks 11. It can be seen in FIG. 1 that the actuator shaft 12, which represents such a rotatably seated actuating element, can be displaced toward the left by means of an only axially displaceable piston 31 for actuating the clamping cheeks 11. For this purpose a pressure medium is supplied via a pressure line 32 to a cylinder chamber formed by the piston 31 and the housing 03. The pressure medium assures that the piston 31 is displaced toward the left and in this way displaces the actuator shaft 12 by acting on the front plate 30, so that as a result the clamping cheeks 11 can be actuated.

[0031] Following the draining of pressure medium from the pressure line 32, the springs 34 assure the return of the actuator shaft 12, so that the piston 31 is pushed back by the front plate 33. The return of the actuator shaft 12 is limited by end stops, so that the front plate 33 can push the piston 31 back only up to a defined point, namely the rearmost working position. In this position the piston 31 still rests against the front plate 33, which is undesirable because of wear occurring in case of a relative movement between the front plate 33 and the piston 31. To prevent this wear, magnetic elements 37, for example a permanent magnet 37, are provided on the front face of the piston 31 facing away from the front plate 33, by means of whose magnetic forces the piston 31 can be returned into a position of rest, in which the piston 31 no longer rests against the front plate 33.

[0032] List of Reference Numerals

[0033]01 Clamping mandrel

[0034]02 Frame

[0035]03 Housing

[0036]04 Rolling bearing

[0037]05 -

[0038]06 Rolling bearing

[0039]07 Shaft, multi-part

[0040]08 Clamping cylinder

[0041]09 Tube

[0042]10 Strip-off ring

[0043]11 Clamping cheek

[0044]12 Adjusting element, actuator shaft

[0045]13 Hollow shaft

[0046]14 Spreading element

[0047]15 -

[0048]16 Adjusting element, part, ejecting bolt

[0049]17 Center axis

[0050]18 Part, piston

[0051]19 Pressure line

[0052]20 -

[0053]21 Intermediate element

[0054]22 Gap

[0055]23 Magnetic element, permanent magnet

[0056]24 Seal ring

[0057]25 Seal

[0058]26 ring

[0059]27 Spring, helical spring 28 End stop 29 Gap 30 Initiator 31 Piston 32 Pressure line 33 Front plate 34 Spring 35 - 36 - 37 Magnetic element, permanent magnet 

1. A clamping mandrel (01) for the rotatable seating of a web wound on a tube (09), having an ejecting device (16, 18) for stripping the tube (09) off the clamping mandrel (01), wherein the ejecting device (16, 18) comprises at least one first element (16) which, together with the tube (09) is seated so it is rotatable around a center axis (17), and a second, not rotatably seated element (18), and wherein the first element (16) can strip the tube (09) off the clamping mandrel (01) by actuating the second element (18), characterized in that the second element (18) is embodied as a piston (18), which can be acted upon by a pressure medium, that in at least one working position, in which the tube (09) can be stripped off, the piston (18) comes to rest on the first element (16), and that in a position of rest the piston (18) is completely separated by a gap (29) from the first element (16).
 2. A clamping mandrel (01) for the rotatable seating of a web wound on a tube (09), having an ejecting device (16, 18) for stripping the tube (09) off the clamping mandrel (01), wherein the ejecting device (16, 18) comprises at least one first element (16) which, together with the tube (09) is seated so it is rotatable around a center axis (17), and a second, not rotatably seated element (18), and wherein the first element (16) can strip the tube (09) off the clamping mandrel (01) by actuating the second element (18), characterized in that the second element (18) is embodied as a piston (18), which can be acted upon by a pressure medium, that the piston (18) is embodied to be circle-shaped and is arranged coaxially in respect to a clamping cylinder (08) of the clamping mandrel (01).
 3. The clamping mandrel (01) in accordance with claim 1, characterized in that the piston (18) is embodied to act on one side, so that the piston (18) can be driven by the fluid for stripping off the tube (09), wherein the piston (18) can be restored by at least one elastic element (27), in particular a spring (27). 